Modulus in Stage construction - Hardening Modelling

Question

I don't know if I did well my model using HS model. 
 In my case the model is related with a dam construction. I used 11 stages. 
 When I verified the modules adopted by Plaxis, I discovered Plaxis used Eur in place of E50. &iquest;Is that correct? 
 I thought the correct way to solve the problem is considering E50 when you put a new layer because you load for first time this layer. Please let me know if I analyze in a good way this problem. 
 The following pictures shows 1. Soil Properties, 2. The section where I reviewed modulus, 3. Graph including: Current Young Modulus (Extracted from Plaxis), Theoretical E50 modulus, Theoretical Eur modulus.

Dennis Waterman · Accepted Answer

Dear Paula, 
 Though the Hardening Soil model has 3 stiffness parameters that are indicated with an "E" (Eoed, E50 and Eur) only the Eur is a Young's modulus (Elasticity modulus) while the other 2 stiffnesses, Eoed and E50, are elastoplastic parameters. When loading, unloading or reloading the soil, the soil will always experience some elastic deformation determined by Eur and the soil may experience also plastic deformation in case of primary loading - the plastic deformation is derived from the values of Eoed and E50. Note that I say here that the Plaxis deformation is DERIVED from Eoed and E50....in fact the HS model doesn't directly use Eoed and E50, it has it's own plasticity parameters called alpha and beta that are determined from the input Eoed and E50 (see the Material Models Manual, chapter on the HS model, for details). Hence, if in PLAXIS Output you check the plot of the current Young's modulus you will see the current Eur that determines the elastic part of the deformation. Because we don't use E50 and Eoed directly in the model, it is not possible to see them in the output. However, that does not mean that PLAXIS only uses Eur for the calculation, the HS model definitely calculates plasticity but it's just not possible to express that into a current Eoed and E50. 
 With kind regards, 
 Dennis Waterman

Modulus in Stage construction - Hardening Modelling

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